Multiple Apple ID logins requested on Son's Macbook and iPhone

I have a client who's child uses his iPhone and Macbook for gaming and downloading apps. There family has three Apple ID logins and periodically each of them has signed into the app store to download an app on the kids device.

The mother would like to separate all of the kids apps from the parents apple ID's or at least not get prompted for multiple apple ID passwords.

Is there a way to know which apps are associated to which apple ID? Would I cloud family sharing resolve this problem?

The mom (CEO) wants the kid to be able to sync to his iTunes and not be prompted for Apple ID logins and Vice versa.

To start, I made sure that the kids account was logged in on both devices (Macbook and iPhone so that going forward he would use his ID for the apps)

Please nothing about parental controls, this isnt a concern and we don't want to use it.

thanks,

Dan